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1 NATIONAL WILDLIFE FEDERATION Sea-level Rise and Coastal Habitats in the Pacific Northwest An Analysis for Puget Sound, Southwestern Washington, and Northwestern Oregon i

2 An Analysis for Puget Sound, Southwestern Washington, and Northwestern Oregon July 27 Prepared by: Patty Glick, Senior Global Warming Specialist, National Wildlife Federation Jonathan Clough, Environmental/Computer Consultant, Warren Pinnacle Consulting, Inc. Brad Nunley, GIS Specialist, National Wildlife Federation 27 by the National Wildlife Federation All rights reserved. Larry J. Schweiger President and Chief Executive Officer National Wildlife Federation Acknowledgements This report is the culmination of the efforts of numerous individuals at the National Wildlife Federation. Special thanks to Dr. Amanda Staudt, James Schroeder, Joelle Robinson, and Tim Warman for shepherding this report through its final edits and coordinating its release. We also sincerely thank Dr. Doug Canning of the School of Marine Affairs and Climate Impacts Group at the University of Washington and Dr. Dick Park of Eco Modeling in Diamondhead, Mississippi, for providing invaluable conceptual and technical guidance throughout this project. Thank you, as well, to Dr. Mary Ruckelshaus, research biologist with the National Oceanic and Atmospheric Administration s (NOAA) Northwest Fisheries Science Center, for reviewing this report. Finally, we are enormously grateful to King County Executive Ron Sims, Elizabeth Willmott, and the King County Executive Action Group on Climate Change for contributing the foreword remarks. Cover photo: Bald eagle at Padilla Bay (NOAA)

4 FOREWORD Global climate change is a reality. Human emissions are driving unprecedented and dangerous climate change, with coastal regions on the front lines of its effects. If we allow climate change to continue unabated, it will have significant effects across the world. Here in the Pacific Northwest, it will jeopardize the health of our most valued natural companions: shellfish, salmon, shorebirds, and waterfowl. As this important report shows, it will also fundamentally alter the way our human community lives on this beautiful coastline, how we get our food, how we interact with nature, and how we live as neighbors to Puget Sound. We can and must change this forecast through aggressive greenhouse gas emissions reductions, while at the same time preparing for its effects on our region. We must set policies that are based on science and data, such as those outlined in the 27 King County Climate Plan, instead of wishful thinking. We must embed climate change assumptions into our natural resource management plans and strategies to enable the most effective environmental restoration and protection possible. Accounting for climate change projections in these plans is important from both a cost perspective and a natural resource perspective, especially for our future generations. As a public official making decisions that impact not only our community today, but also millions of future Puget Sound s residents and their natural environment, I refuse to let future generations pay for the consequences of our current lifestyles. By taking steps today to limit climate change, we can save money, natural resources and the quality of life we all value for our region s future residents tomorrow. This is an imperative. With this report, the National Wildlife Federation reinforces its position of leadership on the most pressing issue facing our human and natural communities today: global climate change. Although the scenarios described in this report may sound gloomy, I am inspired by this honest presentation of one possible future of the Pacific Northwest. Only with such sound science and reason clearly illuminating the problem can we as community leaders and citizens be motivated, empowered and wise enough to cope with and limit the negative consequences of climate change to our beloved coastline. This report advances our collective understanding of that shared future, and I encourage you to read it with that same sense of purpose. RON SIMS, King County Executive i

5 EXECUTIVE SUMMARY The Pacific Northwest is blessed with an amazing diversity of coastal habitats, from rocky bluffs and sandy beaches along the Pacific Coast to the tidal flats, marshes, mixed sediment beaches, and eelgrass beds of Puget Sound. Together, these habitats support thousands of species of fish and wildlife, and they are a linchpin for the regional economy, culture, and quality of life. Despite its pristine image, however, the region s coastal habitats and the ecological systems they support face serious problems due to human activities, which have prompted numerous local and regional restoration and protection efforts. Whether our significant conservation investments will endure for the future depends on how well the region is able to promote more sustainable use of its coastal resources in the face of continued population growth, pressures for development, and now, the very real threat of global warming. Climate Change and Sea-level Rise Scientists have widely and conclusively determined that global warming is happening and that burning fossil fuels is largely to blame. Global warming is disrupting the planet s climate system, and it is already having an impact on the Pacific Northwest. Left unchecked, the region will face higher average air and water temperatures, shifts in precipitation patterns, and a significant decline in average snowpack, all of which will put coastal habitats and the fish and wildlife that depend on them at great risk. In addition, global warming is contributing to a significant increase in the rate of sea-level rise due to the thermal expansion of ocean waters and melting of glaciers and ice fields. Given the vast expanse of coastline along the Pacific Ocean and in Puget Sound and the critical role that vulnerable coastal habitats such as marshes, tidal flats, and beaches play in the region s ecology and economy, sealevel rise is likely to have a profound impact on the Pacific Northwest. Of particular concern is the fact that most of the region s important coastal habitats have already been damaged or destroyed by extensive dredging, coastal modifications, pollution, and other development. Not only does this make remaining habitat all the more important for fish and wildlife, but coastal modifications such as dikes and seawalls have significantly reduced the ability for habitats to migrate inland to accommodate for sea-level rise. Any further losses or changes in habitat composition will have devastating consequences for the region s overall ecological and economic health. Sea-level Rise and Pacific Northwest Coastal Habitats This study investigates the potential impact of sea-level rise on key coastal habitats in the Pacific Northwest. In addition to raising awareness of the threat, the results of the study will assist coastal managers and other relevant decision-makers identify and implement strategies to minimize the risks. We used the Sea Level Affecting Marshes Model (SLAMM), which simulates the dominant processes involved in wetland conversions and shoreline modifications during long-term sea-level rise. This model was applied to 11 different sites in Puget Sound and along the Pacific Coast in southwestern Washington and northwestern Oregon. ii

6 Our analysis looked at a range of Intergovernmental Panel on Climate Change (IPCC) sea-level rise scenarios, from a.8 meter (3. inch) rise in global average sea level by 225 to a.69 meter (27.3 inch) rise by 21. We also modeled a rise of up to 2 meters (78.7 by 21 to accommodate for recent studies that suggest sea-level rise will occur much more rapidly during this century than the IPCC models have projected. Results for each study site are based on relative sea-level rise for the given region, taking into consideration regional changes in land elevation due to geological factors, such as subsidence and uplift, and ecological factors such as sedimentation and marsh accretion. Full model results are available from the National Wildlife Federation. Projected Habitat Changes Model results vary considerably by site (see Table 1), but overall the region is likely to face a dramatic shift in the extent and diversity of its coastal marshes, swamps, beaches, and other habitats due to sea-level rise. For example, if global average sea level increases by.69 meters (27.3, the following impacts are predicted by 21 for the sites investigated: Estuarine beaches will undergo inundation and erosion to the tune of a 65 percent loss. As much as 44 percent of tidal flat will disappear. 13 percent of inland fresh marsh and 25 percent of tidal fresh marsh will be lost. 11 percent of inland swamp will be inundated with salt water, while 61 percent of tidal swamp will be lost. 52 percent of brackish marsh will convert to tidal flats, transitional marsh and saltmarsh. 2 percent of undeveloped land will be inundated or eroded to other categories across all study areas. iii

7 Site 1: Nooksack Delta, Lummi Bay, and Bellingham Bay Table 1. Summary of Results With a 27.3-inch Global Sea-level Rise by 21 Changes to Coastal Habitats (Percentage Changes are Relative to Totals for Each Site) Due to the presence of dikes at this site and relatively high dry land elevations, the majority of effects occur in wetlands southwest of Marietta (Nooksack River Delta), where areas of dry land, swamp, and fresh marsh are likely to transition to saltmarsh. Changes include a 22-percent loss of swamp (including tidal swamp), a 22-percent loss of brackish marsh, and a 42-percent loss of estuarine beach. Site 2: Padilla Bay, Skagit Bay, and Port Susan Bay Site 3: Whidbey Island, Port Townsend, and Admiralty Inlet Site 4: Snohomish Estuary and Everett Site 5: Ediz Hook near Port Angeles through Dungeness Spit and Sequim Bay Site 6: Dyes Inlet, Sinclair Inlet, and Bainbridge Island Site 7: Elliott Bay and the Duwamish Estuary Much of the dry land for this site is protected by dikes and is not subject to inundation. This means that brackish marshes and beaches that are trapped against seawalls may be especially subject to loss, largely through conversion to saltmarsh or tidal flat. By 21, brackish marsh is projected to decline by 77 percent, and estuarine beach by 91 percent. 74 percent of brackish marsh, 29 percent of inland fresh marsh, and a small portion of low-lying dry lands at this site are predicted to be inundated with salt water and converted to saltmarsh and tidal flat. A combination of inundation and erosion is predicted to have significant effects on beaches, especially on western Whidbey Island. This site as a whole is projected to see a 72-percent loss of estuarine beach by 25 and 8-percent loss by 21. Assuming that the extensive dikes in this area are able to withstand the predicted increases in sea-level rise, the most significant change is the inundation of brackish marsh (47-percent loss) and inland fresh marsh (15-percent loss) north of Smith Island and west of Marysville. The region also faces a 74-percent loss of tidal swamp and a 96-percent loss of estuarine beach. Tidal flats at this site are extremely vulnerable, as is Dungeness Spit itself, especially to higher sea-level rise scenarios in which complete loss of the spit is predicted. Additionally, over 58 percent of area beaches (estuarine and ocean together) are predicted to be lost by 21 under all scenarios. Most dry land in this portion of Puget Sound is of sufficient elevation to escape conversion even in the more aggressive sea-level rise scenarios. Over half of beach land is predicted to be lost, however, primarily converted to tidal flats. Saltmarsh and transitional marsh increase, primarily due to loss of dry land. Limited effects are predicted for the Seattle area due to a higher density of development and high land elevations overall. However, 3-4 hectares ( acres) of dry land are predicted to be at risk of being converted to transitional marsh, saltmarsh, and tidal flats. In addition, 55 percent of estuarine beach at this site could be lost by 21 under this scenario. iv

8 Site 8: Annas Bay and Skokomish Estuary Site 9: Commencement Bay, Tacoma, and Gig Harbor Site 1: Olympia, Budd Inlet, and Nisqually Delta Site 11: Willapa Bay, Columbia River, and Tillamook Bay Table 1. (Continued) Changes to Coastal Habitats (Percentage Changes are Relative to Totals for Each Site) High land elevations for dry land and swamp make this site less likely to be influenced by sea-level rise than many of the other sites studied. Even beaches are predicted to have fewer effects than at other sites with roughly one-third lost under all scenarios. The Tacoma area is well protected by dikes around the Puyallup River, so results of sea-level rise are limited near that river. Three to four percent of undeveloped land is predicted to be lost at this site overall, though, converting to transitional marsh and saltmarsh. Over two-thirds of area beaches are predicted to be lost by 21 due to erosion and inundation. The largest predicted changes for this site pertain to the loss of estuarine beach and the inundation of some dry lands. Estuarine beach, in particular, declines by 81 percent. As with the other sites, all developed lands (including Olympia) are assumed to remain protected. This region is predicted to lose at least 5, hectares (12,355 acres) of dry land. There is also likely to be extensive loss of tidal flat and area beaches, especially at higher rates of sea-level rise. Inland and tidal fresh marsh are fairly vulnerable at this site to salt-water inundation. By 21, the site could lose 32 percent of brackish marsh, 31 percent of tidal swamp, 47 percent of estuarine beach, and 63 percent of tidal flats. Impacts on Fish and Wildlife Given the complexity of the Pacific Northwest s coastal and marine systems and the multitude of factors affecting them, it is impossible to know exactly what sea-level rise will mean for the region s fish and wildlife in the decades to come. However, there is no question that these projected changes would fundamentally alter the region s coastal habitats and the species they support. Some species may be able to respond to changes by finding alternative habitats or food sources, but others will not. Furthermore, the larger the changes and rate of change, the harder it will be for most fish and wildlife species to adapt to the impacts of global warming (Inkley, 24). For example, a significant reduction in the area of estuarine beaches would affect important spawning habitat for forage fish, which make up a critical part of the marine food web. Unless species are able to find alternative spawning areas, their populations could decline. Inundation of tidal flats in some areas would reduce stopover and wintering habitat for migratory shorebirds. It could also have a major impact on the region s economically-important shellfish industry. Loss of coastal marshes would affect habitat for thousands of wintering waterfowl that visit the region each year. And changes in the composition of tidal wetlands could significantly diminish the capacity for those habitats to support salmonids, especially juvenile Chinook and chum salmon. v

10 Ducks over Puget Sound (istock) Implications for Coastal Management and Restoration The most important action the region and nation must take to prevent the possibly overwhelming loss of fish and wildlife due to unmitigated global warming is to reduce greenhouse gas emissions. However, there will be some more warming in the next century that we cannot avoid, and this warming will have a significant impact on local species and habitats. Thus, we must also develop adaptation strategies to help fish and wildlife cope with the expected changes to their habitats, including some sea-level rise, as we build in the flexibility to deal with unforeseen impacts. Coastal managers must consider a multitude of factors in their planning efforts, including local ecology and geography, pollution inputs, climate variability and change, population growth, and development trends. By examining the intersection of two important pieces of the coastal management puzzle sea-level rise and critical coastal habitats it is our hope that this study will provide coastal resource managers and other relevant decision-makers with much-needed information about local impacts of sea-level rise on the wildlife of the Pacific Northwest. The results of this study, along with information about other critical stressors on coastal resources, can help decision-makers assess the risks to specific localities and identify reasonable steps to manage these risks. The potential for significant shifts in critical habitat due to sea-level rise illustrated in this report, as well as other likely global warming impacts on fish and wildlife, make it prudent to consider global warming in planning future use of coastal resources. This should include the following: vii

11 1. Account for global warming in habitat restoration efforts. Many efforts are already underway to restore and protect coastal habitats in the Pacific Northwest. Addressing non-climate stressors will help wildlife survive global warming, but explicit consideration of sea-level rise and other climate change impacts will be necessary to ensure that potentially devastating long-term threats do not become a foregone conclusion. There are several strategies that restoration managers should consider, including prioritizing projects based on ecological importance and vulnerability to sealevel rise; expanding the area of restoration to accommodate for habitat migration; restoring a diverse array of habitat types; and addressing upstream stressors that affect sedimentation and other factors that affect how estuarine habitats will respond to sea-level rise. 2. Explicitly consider climate uncertainties. Projections of future climate will always be accompanied by some degree of uncertainty, but this should not be used as an excuse for inaction. In fact, the risk of irreversible damages due to global warming necessitates a precautionary approach to action, much like that applied to anticipating flood hazards. 3. Incorporate sea-level rise in coastal development plans. Sea-level rise and its impacts on habitats and coastal communities should be a major consideration in future development plans. Many steps can be taken to anticipate sea-level rise, including discouraging development in coastal hazard areas, moving or abandoning shoreline infrastructure, preserving ecological buffers to allow inland habitat migration, and enhancing shoreline protection recognizing the negative consequences for shoreline habitat. Ultimately, coastal management decisions must be made in a coordinated, collaborative way at both the local and regional levels. By taking a longer-term, more comprehensive approach to managing and protecting the coastal resources of the Pacific Northwest, we have a real opportunity to prevent the worst-case scenarios from occurring and ensure that the region s treasured natural heritage will endure for generations to come. viii

12 INTRODUCTION The Pacific Northwest is a place rich in history, culture, and natural beauty. Its mere mention evokes images of snow-capped mountains, stately evergreens, scenic rivers, and rugged coasts. The region is also blessed with an amazing diversity of coastal habitats, from rocky bluffs and sandy beaches along the Pacific Coast to the tidal flats, marshes, mixed sediment beaches, and eelgrass beds of Puget Sound. Together, these habitats support thousands of species of fish and wildlife, and they are important for the regional economy and quality of life. Some of the region s most important and productive habitats are in its low-lying river deltas and estuaries the places where rivers and streams meet the sea. Numerous species of shorebirds and migratory waterfowl rely on the shallow waters, tidal flats, and coastal fresh marsh and saltmarshes of estuaries to feed and rest. Estuarine beaches provide vital spawning areas for forage fish, including surf smelt and sand lance, which in turn provide food for birds, marine mammals, salmon, and other fish and wildlife. Thousands of invertebrates, including commercially important oysters and clams, thrive in the mud flats and gravel beds. In addition, estuaries provide critical habitat for juvenile salmon, which spend time there as they acclimate to ocean water. Unfortunately, the majority of the region s coastal wetlands and other estuarine and nearshore habitats have been damaged or destroyed by human activities. According to the Washington State Department of Natural Resources (WADNR), 7 percent of tidally-influenced wetlands in Puget Sound have been damaged or destroyed by urbanization, port development, industrial and agricultural activities, dredging and filling (WADNR, 1998). In addition, an estimated one-third of Puget Sound s shoreline has been modified by seawalls, bulkheads, and other structures. Seawall at Alki Beach in Seattle (Chas Redmond, Flickr.com) 1

13 Similar problems have affected Pacific Coast estuaries in both Washington and Oregon. Habitats of the Columbia River estuary, in particular, have been significantly altered since the mid- 18s due to extensive dredging, construction of dikes, and other development (Independent Scientific Advisory Board, 2). Furthermore, in many of these areas, upstream activities such as flood control and installation of dams for hydroelectric power have dramatically disrupted the natural flow of river sediments into deltas. And the loss of pollutant-filtering coastal wetlands has contributed to a considerable decline in regional water quality, especially in parts of Puget Sound. In recent years, growing signs that the ecological health of the region is in serious decline have bolstered numerous efforts to better protect and restore these important coastal habitats and the fish and wildlife that depend on them, including localized community- and tribal-based projects as well as broad, collaborative government- and stakeholder-driven strategies. Increased investments in land acquisition and habitat restoration, improved watershed planning, and stronger shoreline management have offered considerable hope that, at least in some places, the situation may be turning around (Puget Sound Action Team, 27). For the region as a whole, however, there are still many indicators of a continuing decline in the health of its coastal and marine systems, which underscores the need for a more concerted conservation strategy. In particular, success will strongly depend on how well the region is able to promote more-sustainable use of its coastal resources in the face of continued population growth, pressures for development and now, the very real threat of global warming. 2

14 CLIMATE CHANGE AND SEA-LEVEL RISE Human-enhanced global warming poses a serious threat to the world s natural systems, including those in the Pacific Northwest. According to the IPCC, there is irrefutable evidence that human activities, particularly the burning of fossil fuels and destruction of the world s forests, have been causing excessive amounts of carbon dioxide (CO 2 ) and other greenhouse gases to build up in the atmosphere (IPCC, 27a). As a result, the earth s average surface temperature is rapidly increasing, and the IPCC projects that it will rise by another degrees Celsius ( degrees Fahrenheit) before the end of this century if the nation and world continue to depend extensively on fossil fuels to meet our energy needs. This warming is disrupting the planet s entire climate system. Average water temperatures are becoming warmer, precipitation patterns are changing, and extreme weather events such as droughts, floods, storms, and heat waves are becoming more frequent and severe. Rocky shoreline along Puget Sound (istock) Like many regions, the Pacific Northwest is already beginning to feel the effects of global warming. According to a recent report prepared by the Climate Impacts Group at the University of Washington, the Puget Sound region warmed 1.3 degrees Celsius (2.3 degrees Fahrenheit) during the 2 th century, a rate substantially greater than the global warming trend (Snover, et al., 25, p. 13). In addition, the dates of peak snow accumulation and snowmelt-derived streamflow across the West have shifted by 1-3 days earlier over the past century, and average snowpack has declined significantly (Steward, Cayan and Dettinger, 24). The Cascades, for example, have seen a 3-percent decline in springtime snow water equivalent (the amount of water contained within snowpack) since 1945 (Mote, et al., 25). Without a significant reduction in the pollution that is contributing to global warming, the Pacific Northwest could face even less winter snow accumulation, earlier peak spring streamflows, lower summer streamflows, and elevated water temperatures. 3

15 In addition to disrupting the planet s climate system, global warming is causing sea levels around the world to rise due to a combination of thermal expansion of the oceans and rapidly melting glaciers and polar ice sheets. The global average sea level has already risen about.17 meters (6.7 over the past century, which is about 1-times faster than the rate of sea-level rise over the last 3, years (IPCC, 27a). The rate of sea-level rise is expected to accelerate during this century. Projections vary, but the most recent projections from the IPCC report show an additional meter (7-23- inch) rise in global average sea level by relative to (IPCC, 27a). At the localized level, the relative amount of sea-level rise depends on a number of factors that contribute to vertical land movements, including tectonic processes (subsidence and uplift) as well as sedimentation and marsh accretion (discussed in the following section) (Park, Lee, and Canning, 1993). Uplift, deposition of sediments, and marsh accretion lessen the amount of localized sea-level rise, while subsidence exacerbates the amount of localized sea-level rise. Studies of vertical land movement based on changes in tide gage records show the Puget Sound basin subsiding at rates up to 2. millimeters (.8 per year, while the Pacific Ocean coast along the upper Olympic Peninsula in Washington is uplifting at rates up to 2.5 millimeters (.1 per year (Canning, 26). There are also apparent differences in vertical land movement within Puget Sound, with more subsidence occurring in southern Puget Sound than further north. For example, at Friday Harbor in the San Juan Islands, vertical land movement is close to zero, which means that the rate of sea-level rise at this site (from 1935 to present) has been equal to the global average. In Seattle, on the other hand, land has been subsiding at a rate of about 1.4 millimeters (.6 per year, which makes the rate of sealevel rise for the area roughly double the global average. It should be noted that there is currently some question about whether the local geological subsidence and uplift rates are linear in space and time (i.e., whether they will continue on the current trend into the foreseeable future) (Canning, 27). These new findings have emerged subsequent to our modeling effort, so this project includes the historic rates of vertical land movement in the relative sealevel rise scenarios. For most areas, however, the changes are small, so this factor will not likely have a significant impact on the overall implications of sea-level rise on coastal habitats and infrastructure over the longer-term, particularly under the more aggressive sea-level rise scenarios. In fact, scientists are becoming increasingly concerned that the rate of global sea-level rise in the future could actually be considerably greater than current projections. The latest literature indicates that the global rise in sea levels is progressing more rapidly than was previously assumed, perhaps due to the dynamic changes in ice flow ignored in the latest IPCC report s calculations. Several studies suggest that the rate of ice-sheet decline in Greenland and Antarctica has been accelerating in recent years and that the amount of sea-level rise will be even more pronounced in the future (Chen, Wilson, and Tapley, 26; Otto-Bliesner, et al., 26; Overpeck, et al., 26; Rignot and Kanagaratnam, 26). A paper in the journal Science suggests that, taking into account possible model error, a feasible range by 21 might be meters (2-56 under a 5 degree Celsius (9 degree Fahrenheit) warming relative to 199 levels, which is within the range of projected warming during this century (Rahmstorf, 27). Indeed, sea-level rise of this magnitude would have enormous global consequences. With a large portion of the world s population living in low-lying coastal areas, millions of people will be displaced by sea-level rise before the end of this century. One study, for example, projects that as many as 8 million people will be at risk from coastal flooding (compared to 14 million in the absence of climate change) by 28 with a 3.3 degrees Celsius (6 degrees Fahrenheit) global warming (Parry, et al., 21; Nicholls, 24). This is likely to be particularly devastating for poor countries, the consequences of which should be of utmost concern; but there are also considerable risks closer to home. 4

16 Sea stars (istock) 5

17 SEA-LEVEL RISE AND PACIFIC NORTHWEST COASTAL HABITATS Sea-level rise poses a significant threat to Puget Sound and the Pacific Coast given the sheer extent of the region s shoreline mileage and the fact that some of the most important habitats for fish and wildlife are concentrated in the region s low-lying, tidally-influenced shores and estuaries. According to the 25 report Regional Nearshore and Marine Aspects of Salmon Recovery, many factors determine the distribution pattern and composition of the region s coastal wetlands, tidal flats, seagrass beds, and other nearshore habitats, including their elevation relative to average sea level, inundation, dessication, wave scour, substrate type, and light penetration (Redman, Myers, and Averill, 25). Sealevel rise will affect most of these factors, both directly and indirectly. One of the primary ways in which sea-level rise will affect the region s coastal habitats is through sea-water inundation, which can increase the salinity of the surface and groundwater. Many coastal plant and animal species are adapted to a certain level of salinity, so prolonged changes can make habitats more favorable for some species, less for others. Sea-level rise will also contribute to the expansion of open water in some areas not just along the coasts but also inland, where dry land can become saturated by an increase in the height of the water table. Furthermore, sea-level rise will lead to significant beach erosion and make coastal areas more susceptible to storm surges. Coastal habitats to at least some extent may be able to accommodate moderate changes in sea level by migrating inland. However, the opportunity for inland migration throughout much of the region has been considerably reduced given the accelerating pace of sea-level rise and the fact that much of the region s coasts have been modified by dikes, seawalls, and other armoring. Coastal armoring can also alter the extent of beach erosion associated with wave action. This may be beneficial in terms of protecting coastal property, but it also limits natural beach replenishment. Similarly, for the region s river deltas, natural deposition of river sediments may enable at least some habitats to keep pace with sea-level rise. However, modifications such as dams and levees upstream in many of the region s river basins have significantly limited this sedimentation (Redman, Myers, and Averill, 25). Site specific studies are necessary to supplement the findings of this study to help determine how changes in sedimentation rates associated with upstream activities might affect the localized impacts of sea-level rise. In terms of tidal marsh accretion, a study by Thom, et al. (21) found that most marshes in the Pacific Northwest are generally keeping pace with the current rate of sea-level rise, although again, rates vary by location and the extent of coastal modifications such as diking, which can significantly limit the natural sedimentation and accretion processes. Site-specific factors such as soil types, vegetation types, and the amount of tidal influence are important in determining the potential for submergence of coastal wetlands. As with sedimentation, additional research on changes in accretion rates at the localized level will be important to inform on-the-ground management decisions to address the risks from sea-level rise (Cahoon, et al., 26). It is also important to consider the likelihood that an accelerating rate of sea-level rise due to global warming will significantly limit the ability for marsh accretion in many areas to continue to keep pace with sea-level rise during this century (Morris, et al., 22). 6

18 Damage associated with higher sea level and storm-generated waves during El Niño events illustrates the vulnerability of coastal habitats and property, as seen here on the coast of Oregon near Tillamook Bay. The image above is from October 1997, before storm damage. The image below is the same location on April 1998, after storm damage. (U.S. Geological Survey) Shoreline and dune erosion 7

19 Projected Habitat Changes This study provides the most comprehensive and detailed analysis to date of the potential impacts of sea-level rise on coastal habitats in the Pacific Northwest. We modeled how ten areas in Puget Sound, as well as the Pacific Coast from northeastern Oregon to southwestern Washington would respond to a variety of different sea-level rise scenarios. The model used for this study is called Sea Level Affecting Marshes Model, Version 5. (SLAMM 5.), which was designed to simulate the dominant processes involved in wetland conversion and shoreline modification under long-term sealevel rise (Clough and Park, 27). This model looks beyond the impacts based on coastal topography alone and assesses how sea-water inundation contributes to the conversion of one habitat type to another. It can also assess how much erosion may occur due to changes in wave action. For these reasons, it is an excellent tool for considering how sea-level rise will affect habitats important for the fish, birds, and other wildlife in the region. The section of this report beginning on page 22 includes a more-detailed discussion of the model and sea-level rise scenarios used in this analysis, as well as maps and tables illustrating how each of the 11 study sites is affected under several of the scenarios: an increase of global average sea level of.28 meters (11.2 by 25,.69 meters (27.3 by 21, and 1.5 meters (59.1 by 21. Model results for the additional scenarios considered in this study are available from the National Wildlife Federation. The projections for habitat changes at each of the study sites incorporate differences in the relative sea-level rise for the given region by taking into consideration regional changes in land elevation due to geological factors, such as subsidence and uplift, and ecological factors, such as sedimentation and marsh accretion (see the Appendix). For some of the less developed sites with extensive dikes protecting agricultural and other dry lands, the model was also run without the dikes in place to help inform decisions about removing dikes, which is already happening in some areas as part of coastal restoration efforts. Nearshore habitats in the region are likely to face a dramatic shift in their composition due to sea-level rise (see Table 2). Although there is considerable variability among different sites, the region s coastal landscape is projected to change in significant ways as some habitat types are lost and others expand. Many freshwater marshes and swamps will be converted to saltmarshes or to transitional marshes that experience frequent saltwater inundation. At the same time, significant losses in estuarine beaches, tidal flats, and ocean beach are expected across all scenarios. Furthermore, because all coastal habitats are biologically, chemically, and physically linked, problems that affect even one habitat type is likely to affect the entire coastal system (Restore America s Estuaries, 22). For example, estuaries and bays that experience a net loss in coastal marsh habitat are more likely to face declining water quality because marshes play a critical role in regulating nutrients and filtering pollutants. Algal blooms and other problems associated with excess runoff of nutrients such as nitrogen and phosphorus in coastal waters can cause significant harm to seagrass beds and contribute to hypoxia (low oxygen) events. These and other ecosystem shifts will have major impacts on the overall food web and on individual species, such as Chinook salmon, in ways that are not yet completely understood. Inundation of Freshwater Ecosystems with Saltwater As sea level rises, freshwater ecosystems will increasingly be vulnerable to saltwater intrusion and eventual conversion to saltwater ecosystems. Saltmarsh habitats are predicted to increase overall 8

20 under all scenarios run, due to the conversion of dry land and fresh marsh to saltmarsh. For a 27.3-inch increase in sea level, the area of swamp, and inland and tidal fresh marsh will decrease by over 45 hectares (over 11,2 acres) across all the study sites. At the same time, the area of saltmarsh will increase by over 36 hectares (over 98 acres). Transitional marsh, which is shrub marsh that is now regularly inundated but has not yet converted fully into saltmarsh, will also expand by over 71 hectares (over 19,5 acres). Most coastal plant and animal species are adapted to different levels of salinity, so prolonged changes in salinity can make habitats more favorable for some species, less for others. Even those species that may not be directly sensitive to salinity may be affected if their food mainstays are affected. Because the various coastal habitats are all connected in one way or another, changes in their composition will no doubt have consequences for the coastal ecosystems of which they are a part. The Nisqually delta region, home to the Nisqually National Wildlife Refuge, is one place that is especially susceptible to saltwater inundation, especially if the existing dike structures some of which are protecting freshwater marsh habitat are removed (see Figure 1). It is difficult to predict how this salt water intrusion would affect the salmon and other species that are important to the region. As dikes are already being removed to aid salmon recovery, it will be important to consider how the likely results of sea-level rise will affect these sorts of restoration and conservation efforts. Figure 1 Loss of Beaches and Tidal Flats The beaches and tidal flats of the Pacific Northwest are especially vulnerable to rising sea-level over the next century. Under the 27.3-inch global average sea-level rise scenario, about 65 percent of estuarine beaches and 44 percent of tidal flats are lost across all study sites by 21. In some locations, this will cause significant changes in the coastal landscape. For example, Dungeness Spit is predicted to be subject to inundation, erosion, and overwash due to storm events, leading to major losses of beach and tidal flat habitats (see Figure 2). 9

AP ENVIRONMENTAL SCIENCE 2010 SCORING GUIDELINES Question 4 (a) Based on the rate cited above, calculate the expected increase in sea level, in meters, during the next 50 years. One point can be earned

SECTION 9 How Will Climate Change Affect the Coast and Ocean in Washington? A major driver of climate change impacts on Washington s coasts is sea level rise, which is expected to affect most locations

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